Light-emitting diode lighting device comprising a communication device and installation comprising one such device

ABSTRACT

The lighting device comprises at least one emitter ( 10 ) of white light ( 9 ) produced by an initial radiation ( 1 ) and a secondary radiation ( 2 ), an electronic control circuit ( 11 ) to control the lighting, and a communication circuit ( 12 ). The electronic circuit ( 11 ) controls power supply of the light emitter to emit a modulating light signal ( 3, 4, 31, 36 ) of said initial radiation according to a communication signal ( 13 ). Said modulating light signal is designed to be received by a light signal receiver ( 18 ) sensitive to the initial radiation ( 1 ). A lighting installation comprises a power supply line, at least one lighting device ( 8 ) and at least one electrical apparatus ( 95, 96 ) connected to a receiver ( 18 ) comprising a sensor ( 19 ) sensitive to the initial radiation ( 1 ).

This application is a National Phase Application under 35 U.S.C. 371claiming the benefit of PCT/FR2003/003,433 filed on Nov. 20, 2003, whichhas priority based on France Application No. 02/15,359 filed on12/05/2002

BACKGROUND OF THE INVENTION

The invention relates to a lighting device comprising at least onelight-emitting diode light emitter designed to emit white light byproducing an initial radiation and a secondary radiation resulting fromexcitation of at least one layer of material reacting to said initialradiation, electronic control means connected to said at least onelight-emitting-diode light emitter to control the lighting, and at leastfirst communication means connected to said control means. The inventionalso relates to a lighting installation comprising an electric powersupply line to supply at least one such device.

State of the Art

Known lighting devices comprising a communication device uselight-emitting diodes to emit luminous communication signals.

Such devices are described in particular in U.S. patent application Ser.No. 2002/0,048,177. These devices are used with information display orindication devices in association with sound or visual type receivers.

However, known devices can not be applied for good quality lighting.These lighting devices with colored diodes do not in fact enable a goodcolor rendering to be achieved. Moreover, superposition of communicationsignals is liable to impair the quality of the light and to make changesof color and intensity visible.

In light-emitting diode lighting devices emitting white light, thediodes emit a first light radiation the color whereof is towards theblues or the ultraviolet. The first radiation excites in particular alayer of phosphors or other fluorescent materials, which layer emits asecond radiation in colors of higher wavelength in the visible, forexample towards yellow or green. Mixing of the first and secondradiation thereby gives a white light of good quality to be used forlighting.

However, control of light-emitting diodes emitting white light totransmit communication signals at the same time as emitting the lightfor lighting gives rise to problems of light quality and of transmissionrate. The fluorescence of the phosphors in fact has too great a responsetime to enable transmission of signals of more than 1 megabit persecond. In addition, even with lower speeds, modulation of the firstradiation modifies the white color resulting from mixing of the firstand second radiations.

SUMMARY OF THE INVENTION

The object of the invention is to provide a lighting device comprising acommunication device enabling a high transmission rate and/or a goodquality white light emission, and also an installation equipped withsuch a device.

In a device according to the invention, the electronic control meanscontrol power supply of at least one light-emitting diode light emitterto emit a modulating light signal of said initial radiation according toa communication signal supplied by the first communication means, saidmodulating light signal being designed to be received by light signalreceiver means sensitive to the initial radiation.

In a preferred embodiment, the lighting device comprises receiver meanscomprising a sensor sensitive to the initial radiation connected toreceipt signal processing means.

Advantageously, the receiver means comprise optical filtering means tolet a light signal corresponding to an initial radiation pass and toreject a secondary radiation.

Preferably, the receiver means comprise electronic filtering means toreduce or eliminate a DC component of a signal representative of anoptical signal received by the receiver means.

Preferably, the electronic control means control power supply of atleast one light-emitting diode light emitter to emit a modulated lightsignal of said initial radiation by superposing a DC component and amodulation signal representative of a communication signal.

Advantageously, the DC component depends on a value representative ofthe communication signal.

Advantageously, the amplitude of the modulation signal depends on avalue representative of the communication signal.

Advantageously, the electronic control means comprise compensation meansto compensate lighting color drifts.

In a particular embodiment, the lighting device comprises at least onered light-emitting diode light emitter and/or at least one bluelight-emitting diode light emitter controlled by the electronic controlmeans.

Preferably, the electronic control means comprise means for controllingthe color temperature of the light.

Advantageously, the lighting device comprises at least one light sensorconnected to the control means to regulate the light intensity, thecolor rendering index and/or the color temperature of a light intendedfor lighting.

Advantageously, the lighting device comprises at least one currentsensor to supply to the control means a signal representative of acurrent flowing in at least one emitter and to regulate a current to besupplied to said emitter.

A lighting installation according to an embodiment of the inventioncomprises an electric power supply line to supply at least one lightingdevice as defined above and at least one electrical apparatus connectedto a receiver comprising a sensor sensitive to the initial radiation.

Advantageously, said receiver is integrated in said at least oneelectrical apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages and features will become more clearly apparent from thefollowing description of particular embodiments of the invention, givenas non-restrictive examples only and represented in the accompanyingdrawings, in which:

FIG. 1 represents a light spectrum able to be emitted by a whitelight-emitting diode emitter;

FIG. 2 represents an example of communication signals;

FIG. 3 illustrates the aspect of the light intensity of a first and asecond radiation controlled by a signal representative of acommunication signal;

FIG. 4 represents a lighting device according to an embodiment of theinvention;

FIGS. 5A, 5B and 5C represent signals in a lighting device according toan embodiment of the invention without compensation;

FIGS. 6A, 6B and 6C represent signals in a lighting device according toan embodiment of the invention with compensation;

FIG. 7 represents a lighting device according to an embodiment of theinvention also comprising diodes emitting colored lights;

FIG. 8 represents a diagram of a control circuit of a lighting deviceaccording to an embodiment of the invention;

FIG. 9 represents a modelling diagram of the functions of a diodeemitting white light;

FIG. 10 represents a first compensation diagram of a lighting deviceaccording to an embodiment of the invention;

FIG. 11 represents a second compensation diagram of a lighting deviceaccording to an embodiment of the invention;

FIG. 12 represents a regulation diagram of a lighting device accordingto an embodiment of the invention;

FIG. 13 represents an installation comprising an apparatus and a deviceaccording to an embodiment of the invention;

FIG. 14 represents signals able to be emitted by a device according toan embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows a light spectrum able to be emitted by a white lightlight-emitting diode usable in a device according to the invention. Insuch a diode, a first radiation is emitted in the blue or theultraviolet, for example centered on a wavelength of 460 nanometers. Asecond radiation is re-emitted by a fluorescent layer in particular madeof phosphor excited by the first radiation. The second radiation is forexample in the greens or yellows, for example centered on 550nanometers. Mixing these two radiations produces a white light usablefor lighting.

FIG. 2 shows an example of a communication signal frame able to modulatea first radiation emitted by the white light-emitting diodes. The firstradiation 1 has a fast response time and enables data to be transmittedwith a fast transmission rate.

In FIG. 3, a first radiation 1 represented by a curve 4 has a fastresponse and a second radiation represented by a curve 5 follows thefirst radiation with a slower response. If a communication signal 3varies little as in a first part 6 of FIG. 3, the second radiation 2 canreach a sufficient value and not impair the white light too much. In thecase where the variation is fast, as in the second part 7 of the curvesof FIG. 3, the first radiation is at its maximum value but the secondradiation cannot reach its normal lighting value. In the part 7, thebrightness of the device decreases and the color rendering becomes poorbecause a component of the white light decreases greatly. Moreover, theslow reaction of the second radiation is liable to disturb radiationsensors designed to receive optical communication signals.

In a lighting device 8 according to an embodiment of the inventionrepresented in FIG. 4, light-emitting diode light emitters 10 designedto emit white light 9 are connected to an electronic control circuit 11.A communication circuit 12 is connected to the control circuit to supplycommunication signals 13 and to a communication line 14 to receivesignals to be transmitted. The electronic control circuit 11 isconnected to a power supply line 15 to receive electric power. When theyare supplied by the control circuit, the light emitters 10 produce aninitial radiation 1 and a secondary radiation 2 resulting fromexcitation of at least one layer 16 of material reacting to said initialradiation. The control circuit thus controls the lighting and commandspower supply of the light-emitting diode light emitters 10 to emit amodulating light signal 17 of said initial radiation 1 according to acommunication signal 13 supplied by the first communication means 12.Said modulating light signal 17 is designed to be received by a lightsignal receiver 18 sensitive to the initial radiation 1.

The receiver 18 comprises a sensor 19 sensitive to the initial radiationconnected to a processing circuit 20 to process receipt signals 21. Anoptical filter 22 is arranged in front of the sensor 19 to let a lightsignal corresponding to an initial radiation 1 pass and to reject asecondary radiation 2.

Advantageously, the processing circuit 20 comprises an electronic filter28 to reduce or eliminate a DC component of a signal representative ofan optical signal received by the receiver sensor 19. An output signal98 of the processing circuit is supplied to a communication circuit 23of the receiver which in turn supplies signals 24 usable by a functionsmodule 25 of the receiver.

The control circuit 11 preferably comprises an input to receive signals26 supplied by a light sensor 27. Thus, the circuit 11 can regulate indynamic manner the light intensity, the color rendering and the colortemperature according to the light received by the sensor. Such aregulation enables the light produced but also the ambient light whichmay exist in a lighted room to be taken into account. This sensor can beof the photodiode or color sensor type. In this case, the signal 26 willcomprise three signals representative of three colors, for example red,green and blue.

FIGS. 5A to 5C show signals in a non-compensated device. A curve 30 ofFIG. 5A illustrates a communication signal 13, a curve 31 of FIG. 5Billustrates an optical signal produced by the initial radiation 1 and acurve 32 illustrates the aspect of a secondary radiation 2. The initialradiation 1 will be received and used for communication. The secondaryradiation is used in combination with the initial radiation to producewhite light. In the case of FIGS. 5A to 5C, communication is performedrapidly but the color rendering may still be disturbed.

In an advantageous embodiment, the control circuit 11 controls thelight-emitting diode light emitters 10 to emit a light signal of saidinitial radiation by superposing a DC component and a modulation signalrepresentative of a communication signal.

FIGS. 6A to 6C show signals of a compensated device. A curve 33 of FIG.6A illustrates a communication or control signal 13 comprising a DCcomponent 34 and a modulated part 35, a curve 36 of FIG. 6B illustratesan optical signal produced by the initial radiation 1 with a DC part 37and a variable part 38, and a curve 39 illustrates the aspect of asecondary radiation 2. The secondary radiation is much less disturbedand regulation can be performed more easily by varying the value of theDC component 34 or 37. Thus, the brightness, color rendering and colortemperature are very stable and very little dependent on thecommunication signal.

To improve control of the color rendering and color temperature, adevice according to an embodiment of the invention, represented in FIG.7, comprises light-emitting diode emitters 40 of red light 41 andlight-emitting diode emitters 42 of blue light 43 controlled by thecontrol circuit 11.

FIG. 8 represents a block diagram of a control circuit 11. In thisdiagram, a power supply circuit connected to the line 15 supplies thelight emitters 10, 40 and 42 via electronic power circuits respectively46, 47 and 48.

A control and regulation circuit 49 receives communication signals 13and commands the electronic power circuits according to valuesrepresentative of said signals. Current sensors 50, 51 and 52 supply thecircuit 49 with signals representative of currents flowing in the lightemitters respectively 10, 40 and 42. Control and regulation arepreferably performed according to parameters 53 supplied to the circuit49. For example the parameters can be recorded in a memory circuit.

A light sensor 27 is connected to the circuit 49 to enable efficientregulation of the light intensity, of the color rendering index and/orof the color temperature. Other sensors 54 can supply control signals 55to the circuit 49. For example, the sensor 54 can be a presence detectorenabling the lighting device to be switched on or switched off dependingon the presence or not of a person in a detection zone. The arrangementof the sensor can depend on the use, for example the sensor can bearranged near to the lighting device or be located remotely in a moresuitable place. The sensor can also be arranged on a work table or on adesk. It will then be advantageously linked to the control device by awireless link, in particular by a radio or infrared link.

Control signals 60, 61 and 62 applied by the circuit 49 to theelectronic power circuits respectively 46, 47 and 48 can thus depend onseveral signals or events.

The diagram of FIG. 9 shows a functional modelling of a light-emittingdiode emitting white light. A block 70 represents the generator of theinitial radiation 1 output from the optical emitter and a block 71represents a generator of secondary radiation 2 produced by afluorescent layer of phosphors. The resulting white light 9 is thecombination of the radiations 1 and 2.

In a compensation device, the value of the DC component is adjusted tokeep substantially constant light characteristics. FIG. 10 shows aregulation system enabling a control signal 60 to be supplied to whitelight emitters clamped to a signal 13 representative of a communicationsignal. Thus, a detection and correction module 72 receives the signal13 and supplies a DC component signal 73 to an operator 74. Saidoperator 74 combines the signal 13 and the signal 73 to supply thecontrol signal 60 controlling the circuit 46. The DC component 73 can bedetermined notably according to the mean value, the rms value, thefrequency and/or the duty cycle of the signal 13.

In a regulation system represented in FIG. 11, a module 72 performscorrection of the DC component by supplying a signal 73, and a module 75receiving the signal 13 performs correction of the amplitude of thevariable signal by supplying a modulation signal 76 the amplitudewhereof varies according to the input signal 13. The signals 73 and 76are applied to an operator 77 which supplies a signal 78 comprising a DCcomponent and a variable communication signal corrected according to theinput signal 13. The signal 78 can be applied to the circuit 46 ascontrol signal 60. However, correction can be completed by a colorcorrection module 79 receiving the signal 13 and supplying a signal 80to correct the color rendering and/or the color temperature. The signal80 is combined with the signal 78 in an operator 81 to supply thecontrol signal 60. The module 79 can also control blue or red lightdiodes by supplying control signals 61 and 62.

FIG. 12 shows a regulation system also performing regulation accordingto currents flowing in the light emitters. Thus, a regulation module 85receives a communication signal 13 and a signal 86 representative of acurrent flowing in white light light-emitting diodes supplied by thesensor 50. The module 85 performs regulation and supplies a signal 87containing a DC component and a variable part dependent on the signal 13and on the current signal 86. A color correction module 88 receives asignal 26 from a light or color sensor 27 and signals 89 and 90 suppliedby the current sensors respectively 51 and 52. The module 88 performscolor correction according to the signals 26, 89 and 90 and supplies acorrection signal 91 to correct control of the white light emitters andsignals 61 and 62 to control the red and blue light emitters. Anoperator 92 combines the signals 87 and 91 to supply a control signal 60of the white light emitters. Advantageously, such a device achieves avery efficient compensation of the light intensity, of the colorrendering index and of the color temperature.

FIG. 13 shows an installation comprising a lighting device 8 accordingto an embodiment of the invention connected to an electric power supplyline 15 and to an electric apparatus 95 connected to a receiver 18comprising a sensor sensitive to the initial radiation 1. Said receiver18 can also be integrated in a receiver 96 to receive communicationlight signals.

The electric apparatuses can be in particular computers, multimediaequipment, or portable equipment, in particular video or soundequipment.

FIG. 14 shows signals also able to be used in lighting devices where thevariation and adjustment of the brightness are performed by pulse widthmodulation or by variation of the diode lighting cycle. Thus, the DCcomponent 37 can be modulated at low frequency to control the lightingintensity and the variable component 38 representative of thecommunication signal to be emitted by radiation is superposed on thesignal 37.

In the devices described above, the light emitters are representedoperating in direct lighting. However, they can advantageously comprisean optical light or color distribution, diffusion and/or mixing deviceto improve the quality of the light. Furthermore, the light emitters canbe numerous and be arranged in the form of a matrix and/or beconstituted by high power emitters arranged at the periphery of adistribution device.

1. A lighting device comprising: at least one light-emitting diode foremitting white light by producing an initial radiation and a secondaryradiation resulting from excitation of at least one layer of materialwhich reacts to said initial radiation; an electronic controller forcontrolling the lighting connected to said at least one light-emittingdiode; at least one communication means for transmitting data connectedto said electronic controller; and a light signal receiver sensitive tothe initial radiation and able to receive a modulating light signal fromsaid at least one light-emitting diode; wherein the electroniccontroller controls a power supply of at least one light-emitting diode,said at least one light-emitting diode for emitting a modulating lightsignal of said initial radiation according to a communication signaltransmitted by the at least one communication means.
 2. A lightingdevice according to claim 1 comprising a receiver comprising a sensorsensitive to the initial radiation connected to a receipt signalprocessor.
 3. A lighting device according to claim 2 wherein thereceiver comprises an optical filtering means to let a light signalcorresponding to an initial radiation pass and to reject a secondaryradiation.
 4. A lighting device according to claim 2 wherein thereceiver comprises at least one electronic filter to reduce or eliminatea DC component of a signal representative of an optical signal receivedby the receiver.
 5. A lighting device according to claim 1 wherein theelectronic controller controls a power supply of at least onelight-emitting diode for emitting a modulated light signal of saidinitial radiation by superposing a DC component and a modulation signalrepresentative of a communication signal.
 6. A lighting device accordingto claim 5 wherein the DC component depends on a value representative ofthe communication signal.
 7. A lighting device according to claim 5wherein the amplitude of the modulation signal depends on a valuerepresentative of the communication signal.
 8. A lighting deviceaccording to claim 7 wherein the electronic controller comprises a meansfor compensating lighting color drifts.
 9. A lighting device accordingto claim 1 comprising at least one red light-emitting diode and/or atleast one blue light-emitting diode controlled by the electroniccontroller.
 10. A lighting device according to claim 1 wherein theelectronic controller comprises a light color temperature controller.11. A lighting device according to claim 1 comprising at least one lightsensor connected to the electronic controller for regulating at leastone of the light intensity, the color rendering index and/or the colortemperature of a light intended for lighting.
 12. A lighting deviceaccording to claim 1 comprising at least one current sensor forsupplying to the electronic controller a signal representative of acurrent flowing in at least one emitter, to regulate a current to besupplied to said emitter.
 13. A lighting installation comprising anelectric power supply line for supplying at least one lighting devicecomprising at least one lighting device according to claim 1 and atleast one electrical apparatus connected to a receiver comprising asensor sensitive to the initial radiation.
 14. A lighting installationaccording to claim 13 wherein said receiver is integrated in said atleast one electrical apparatus.